Device for cleaning air passage openings in the walls of a refuse burning furnace

ABSTRACT

An air passage in the wall of a refuse burning furnace is cleaned by means of a sleeve, which normally is used for governing the air flow by axial displacement of one of its ends within the passage proper. This sleeve is mounted so it can be occasionally pushed right through the passage and furthermore in such a manner that air is prevented, in use, from passing into the sleeve, whereby the latter may be used for inspection purposes.

United States Patent Astrt'im 14 1 Apr. 8, 1975 i 1 DEVICE FOR CLEANINGAIR PASSAGE [56} References Cited OPENINGS IN THE WALLS OF A REFUSEUNlTED STATES PATENTS BURNING FURNACE 2.480394 8/!949 Cavers et al.200/42 x 5 1 Q t 3.043.250 7/1962 Nyberg 0. 122/235 x [7 1 Memo Astmm Semngwnd 3.361.419 1/1966 Siemsscn 200/42 x 3.742.916 7/l973 Wessberg etal l Ill/I815 [73] Assignee: Gotaverken Angteknik AB.

Goteborg Sweden Primary Examiner-Kenneth W. Sprague I22 Filed. Feb 201974 Almrnev, Agent, or Firm-Holman & Stern [21] App]. No.: 444.152 [57]ABSTRACT An air passage in the wall of a refuse burning furnace 30Foreign Appncafio. p Data is cleaned by means of a sleeve. whichnormally is Mar 5 '97.; Sweden 019mg used for governing the air flow byaxial displacement of one of its ends within the passage proper. This 52I IIIIIIIII u 2.5 sleeve is mounted so it can be occasionally pushed I US u 22/235 42,? right through the passage and furthermore in such a l inCI F22b37/48 manner that air is prevented. in use. from passing into 5 a266/41 the sleeve. whereby the latter may be used for inspectionpurposes.

3 Claims, 4 Drawing Figures PATENTEUAPR 8IHT5 SHEET 1 OF 3 FIG.]

PATENTEDAFR' 81% sum 2 or 3 FIG.2

DEVICE FOR CLEANING AIR PASSAGE OPENINGS IN THE WALLS OF A REFUSEBURNING FURNACE BACKGROUND OF THE INVENTION With many kinds of refuseburning furnaces the combustion air is supplied through a number ofpassages in the walls of the furnace, with said passages being connectedto a common air supply conduit in groups. so called registers.Especially with furnaces adapted for the combustion of waste liquor fromcellulose pulp manufacture, the air passages will be rapidly cloggedpartly by matter contained in the combustion gases and partly by slagproducts running down the furnace walls.

Different ways of cleaning these passages have been proposed during theyears. including mechanical scraping devices as well as arrangements fordirecting the flow of combustion air in such a manner that a blasting ofthe faces most likely to be clogged is obtained.

One embodiment of last mentioned type includes a sleeve which isdisplaceable towards and away from the passage and which directs astream of air branched off from the volume of air alloted to thepertaining passage. so it is forced to flow along the walls of thepassage. A device of this type will show fine cleaning results, but itsuffers from two disadvantages.

On the one hand, it is necessary to vary the main body of air dependingupon the occasional combustion intensity, and as the cleaning occursthrough a (small) branched stream of the total volume, it will either benecessary to adjust two streams. or to accept the fact that the blastingwill not be uniform during all operating conditions.

On the other hand, it is necessary, occasionally to lance the fuel bedwithin the furnace through an air passage. The air supply conduit mustthen, with this type of cleaning device as well as with other knowndevices, be opened to permit the introduction ofa lancing tool. Theoperator will then have to face a jet of hot air. possibly mixed withgas. blowing out through the opening in the air conduit.

SUMMARY OF THE INVENTION A more uniform cleaning and a full avoidance ofthese backwardly directed air streams is, according to the invention,attained if the sleeve is sealingly fitted into the air conduit, and isdisplaceable with respect to a guiding means within the same. The end ofthe sleeve remote from the furnace. being is accessible from outside theconduit. and the arrangement further is such that air is prevented fromentering the sleeve.

The full volume of air to be supplied through the pertaining passagewill then pass out through the annular passage between the sleeve andthe wall of the passage. Even the smallest possible volume of air willthen be larger than the cleaning stream branched off with the older typeofdevice. As the air flows outside the sleeve an ejector action iseffected which will cause a subpressure within the sleeve. When thelancing opening is used. an inflow of air from the boiler house into thesleeve is obtained instead of the previous back blow of hot air. Thelancing operation will. therefore, be much easier.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of aportion of the wall of furnace for the combustion of waste liquor,

FIG. 2 shows a longitudinal section through an air passage withgoverning means.

FIG. 3 shows a section corresponding to FIG. 2, through a modifiedembodiment. and

FIG. 4 shows a further arrangement using this embodiment.

DESCRIPTION OF SOME PREFERRED EMBODIMENTS The wall of the furnace issupported by a number of water cooled tubes 10, which are weldedtogether by means of fins 11 in such a manner that a gas tight structureis obtained. This is, towards the furnace, covered by a protectingcladding of known type, not shown here.

A number of air passages. 12 have been provided at suitable positions inthe wall, with each passage being formed by bending two tubes away fromeach other.

These passages are, depending upon the type and the size of the furnace,combined into registers for the supply of primary and secondary air,respectively. The passages are, in connected to conduits I3 supplyingpreheated air.

In order to make possible an individual adjustment of the air flowingout through a passage. a sleeve 14 is provided therein and arranged insuch a manner that it can be axially displaced towards and away from thefurnace wall. A wall 15 defining the air passage is formed in such amanner that the cross section of the passage will decrease in thedirection of flow. but may form a parallel terminal portion at the mouthof the passage.

The position of sleeve 14 within the passage will thus determine thesize of the annular passage through which the air may flow out into thefurnace. This outflow will thus occur adjacent to the wall of thepassage only. and a strong blasting of the wall face will thus bebrought about, so dry matter as well as droplets of slag will be blownaway.

The sleeve 14 is telescopically displaceable in a guide means 16 whichis fitted into the air supply conduit 13, here a branch part connectedthereto. Between the guide means 16 and the sleeve 14, a resilientcollar 17 is provided. which prevents air from the conduit entering thesleeve.

The guide means 16 extends outside the wall of the supply conduit, soits end wall 18 will be accessible outside the conduit. but otherwise ishermetically fitted therein.

In the end wall of the guide means. an elongated. screw threaded member19 is fitted. and by means of which the sleeve 14 may be operated. Theend wall fur ther carries a window 20, which is directed in such amanner that it is possible to look into the furnace through the guidemeans and the sleeve. so a portion of the fuel bed may be watched.

The end wall 18 further contains a lancing opening 21, which makespossible the introduction of a rod like too] into the furnace in orderto work the fuel bed or to break away difficult accumulations of slag,which accidentally may have collected in the air passage, in spite ofthe forceful air blasting above described.

As all air is flowing out around the mouth of the sleeve, a subpressurewill be caused therein as well as in the guide means. When the lancingopening is used no disagreable blackblowing" of hot air will occur.which hitherto has been a source of trouble and also has caused injuriesof the staff and damaged equipmentv The lancing opening is normallyclosed by a tophinged lid 22 and it is sufficiently heavy to remainclosed in spite of the sub-pressure. The lid will automatically be swungaside when the tool is introduced.

The sleeve 14 and the screw 19, respectively. have such a length thatthe end of the sleeve. turned towards the furnace. may be brought rightthrough the passage. The sleeve may. in this manner. be used to scrapeaway collections of matter at the mouth of the passage.

FIG. 3 shows a first modification of the device. The sleeve 14 is. hereby means of a bellows 30, connected to the back wall of the air conduit13:: and is carried by a support 31, which runs in a guide means 32.This is. in turn. carried by a bracket 33 within the air conduit 13. Thescrew 19 is connected with the support 31 and can. in the same manner asdescribed in connection with the previous embodiment. displace thesleeve to wards and away from the opening 15. The bellows makes thesemovements possible without any air leaking into the sleeve from thesurrounding air conduit.

Outside the air conduit proper 13a. there is a further conduit 34. whichis connected to at least some of the sleeves [4. Within a cellulose pulpmill. there are a number of devices. for instance mixer tanks. fromwhich mist or vapor containing chemicals will issue. and which it may bedifficult to ventilate away.

The conduit 34 is connected to one or more ofthese devices located nottoo far away from the furnace. The sub-pressure in the sleeve 14 issufficient to draw these vapors into the furnace where they will bedestroyed and some chemicals possibly reclaimed.

The inspection windovi 20 and the lancing opening 2] are here mounted ina hinged lid 35. whereby full access is made possible. should such berequired. In stead offitting the additional conduit 34 outside the airconduit 13a. it may be located inside the same and be connected tosleeve 14 downstream ofthe bellows. The additional conduit 34 will thenalso have to include a resilient portion so it can follow the movementsof the sleeve.

FIG. 4 shows a special use. or a further development. of the arrangementaccording to FIG. 3. The sleeve 14 is here dimensioned in a manner topermit the introduction ofa camera 36 of TV-type. about to its mouth.The camera is maintained in a desired position by means of a chain 40.and transfer of the pictures is made by way of cables 37. connected to amonitoring device of known type (not shown).

The air flowing around the sleeve 14 will maintain the temperatureadjacent to the camera at a constant. known value. A cooling of thecamera itself is obtained by means of air supplied through a hose 38enclosing the cables 37. On this occasion. a specially formed lid 39 isused to close the extending end of the sleeve.

By mounting a number of cameras in suitably posi tioned air passages. itwill be possible to follow the combustion on the fuel bed from acentrally located operating post. which has hitherto been impossible.

in this manner. it is simple to follow the influence of different kindsof liquor spraying nozzles and of air inlet arrangements. as well ofdifferent pressures and inlet velocities of the liquor and the air.respectively. With a continuous survey. it is possible to control thecombustion, and to make rapid adjustments if tendencies to incompletecombustion should occur for instance due to an unstable flame or aleaking tube. A fully developed monitoring system may include aprogrammed governing unit determining the supply of liquor and air. aswell as possible additional fuel. in an optimal manner depending uponvariations of selected parameters.

Besides with waste liquor combustion furnaces, the invention may be usedwith other types of furnaces for the combustion of refuse causing a highdegree of ash products having a tendency of clog the air passages. Thesize and the shape of the latter as well as the grouping thereof to theair conduits will have to be suited to size and the capacity of thefurnace. As the sleeve and its guide are fully defined with respect tothe air conduit. it is not necessary to lower the air pressure during alancing operation and such activity at one passage will thus notdetrimentally influence the flow of air to adjacent passages.

What I claim is:

1. In a refuse burning furnace. walls defining the furnace. a number ofcombustion air passage openings in the walls. conduit means outside saidwalls for supplying air to said passages openings and means. at least atsome of said passages openings. for mechanically scraping the passageopenings. said means including a sleeve extending into and being axiallydisplaceable with respect to the pertaining passage opening. theimprovement of means defining the passage opening so as to present across-section decreasing in the direction of flow. means forhermetically mounting the end of the sleeve remote from the wall withrespect to the conduit. and further means for making the end of thesleeve remote from the wall accessible from outside the air conduit.

2. The refuse burning furnace according to claim 1, in which a conduitconnected to a source generating mist. gases or vapor and locatedadjacent to the furnace is connected to the sleeve.

3. The refuse burning furnace according to claim 1, including a cameradevice for monitoring the combustion and in which the sleeve has suchdimensions and the further means for making the end of the sleeve remotefrom the wall accessible is arranged so as to permit the introductioninto the sleeve about to the inner end thereof. of said cameral device.

1. In a refuse burning furnace, walls defining the furnace, a number ofcombustion air passage openings in the walls, conduit means outside saidwalls for supplying air to said passages openings and means, at least atsome of said passages openings, for mechanically scraping the passageopenings, said means including a sleeve extending into and being axiallydisplaceable with respect to the pertaining passage opening, theimprovement of means defining the passage opening so as to present acrosssection decreasing in the direction of flow, means for hermeticallymounting the end of the sleeve remote from the wall with respect to theconduit, and further means for making the end of the sleeve remote fromthe wall accessible from outside the air conduit.
 2. The refuse burningfurnace according to claim 1, in which a conduit connected to a sourcegenerating mist, gases or vapor and located adjacent to the furnace isconnected to the sleeve.
 3. The refuse burning furnace according toclaim 1, including a camera device for monitoring the combustion and inwhich the sleeve has such dimensions and the further means for makingthe end of the sleeve remote from the wall accessible is arranged so asto permit the introduction into the sleeve about to the inner endthereof, of said cameral device.